1,185 research outputs found
Coherent control for the spherical symmetric box potential in short and intensive XUV laser fields
Coherent control calculations are presented for a spherically symmetric box
potential for non-resonant two photon transition probabilities. With the help
of a genetic algorithm (GA) the population of the excited states are maximized
and minimized. The external driving field is a superposition of three intensive
extreme ultraviolet (XUV) linearly polarized laser pulses with different
frequencies in the femtosecond duration range. We solved the quantum mechanical
problem within the dipole approximation. Our investigation clearly shows that
the dynamics of the electron current has a strong correlation with the
optimized and neutralizing pulse shape.Comment: 11 Pages 3 Figure
Type Iax SNe as a few-parameter family
We present direct spectroscopic modeling of five Type Iax supernovae (SNe)
with the one dimensional Monte Carlo radiative transfer code TARDIS. The
abundance tomography technique is used to map the chemical structure and
physical properties of the SN atmosphere. Through via fitting of multiple
spectral epochs with self-consistent ejecta models, we can then constrain the
location of some elements within the ejecta. The synthetic spectra of the
best-fit models are able to reproduce the flux continuum and the main
absorption features in the whole sample. We find that the mass fractions of
IGEs and IMEs show a decreasing trend toward the outer regions of the
atmospheres using density profiles similar to those of deflagration models in
the literature. Oxygen is the only element, which could be dominant at higher
velocities. The stratified abundance structure contradicts the well-mixed
chemical profiles predicted by pure deflagration models. Based on the derived
densities and abundances, a template model atmosphere is created for the SN Iax
class and compared to the observed spectra. Free parameters are the scaling of
the density profile, the velocity shift of the abundance template, and the peak
luminosity. The results of this test support the idea that all SNe Iax can be
described by a similar internal structure, which argues for a common origin of
this class of explosions.Comment: 21 pages, 7 tables, 16 figures, accepted by MNRA
Vasopressin deficiency diminishes acute and long-term consequences of maternal deprivation in male rat pups.
Early life events have special importance in the development as postnatal environmental alterations may permanently affect the lifetime vulnerability to diseases. For the interpretation of the long-term consequences it is important to understand the immediate effects. As the role of vasopressin in hypothalamic-pituitary-adrenal axis regulation as well as in affective disorders seem to be important we addressed the question whether the congenital lack of vasopressin will modify the stress reactivity of the pups and will influence the later consequences of single 24h maternal deprivation (MD) on both stress-reactivity and stress-related behavioral changes. Vasopressin-producing (di/+) and deficient (di/di) Brattleboro rat were used. In 10-day-old pups MD induced a remarkable corticosterone rise in both genotypes without adrenocorticotropin (ACTH) increase in di/di rats. Studying the later consequences at around weaning (25-35-day-old rats) we found somatic and hormonal alterations (body weight reduction, dysregulation of the stress axis) which were not that obvious in di/di rats. The more anxious state of MD rats was not detectable in di/di rats both at weaning and in adulthood (7-12-week-old). The lack of vasopressin abolished all chronic stress and anxiety-like tendencies both at weaning and in adulthood probably as a consequence of reduced ACTH rise immediately after MD in pups. This finding suggests that postnatal stress-induced ACTH rise may have long-term developmental consequences
Presynaptic Protein Synthesis Is Required for Long-Term Plasticity of GABA Release
Long-term changes of neurotransmitter release are critical for proper brain function. However, the molecular mechanisms underlying these changes are poorly understood. While protein synthesis is crucial for the consolidation of postsynaptic plasticity, whether and how protein synthesis regulates presynaptic plasticity in the mature mammalian brain remain unclear. Here, using paired whole-cell recordings in rodent hippocampal slices, we report that presynaptic protein synthesis is required for long-term, but not short-term, plasticity of GABA release from type 1 cannabinoid receptor (CB1)-expressing axons. This long-term depression of inhibitory transmission (iLTD) involves cap-dependent protein synthesis in presynaptic interneuron axons, but not somata. Translation is required during the induction, but not maintenance, of iLTD. Mechanistically, CB1 activation enhances protein synthesis via the mTOR pathway. Furthermore, using super-resolution STORM microscopy, we revealed eukaryotic ribosomes in CB1-expressing axon terminals. These findings suggest that presynaptic local protein synthesis controls neurotransmitter release during long-term plasticity in the mature mammalian brain
Di-cationic arylimidamides Act Against Neospora caninum tachyzoites by Interference in Membrane Structure and Nucleolar Integrity and are Active Against Challenge Infection in Mice
Neospora caninum is considered to be the main cause of bovine abortion in Europe and the USA, leading to considerable financial impact. Losses are caused directly by abortions or indirectly through breeding of calves with impaired viability. Due to the lack of effective chemotherapy against bovine neosporosis, there is a need to develop new anti-protozoal compounds, which would either eliminate the parasite or avoid its transmission. In order to identify compounds of interest, the in vitro activities of 41 di-cationic pentamidine derivatives were studied employing a transgenic N. caninum clone expressing beta-galactosidase as a reporter gene. The arylimidamide DB745, previously shown to be highly active against Leishmania donovani in vitro and in vivo, appeared as the most promising compound, with an IC50 of 80 nM in 3-day growth assays and severely affecting both host cell invasion as well as intracellular proliferation. TEM of intracellular tachyzoites identified distinct alterations related to the nucleolus and the nuclear and cellular membrane. Long-term growth assays showed that DB745 acted parasiticidal upon the Nc-Liv isolate, but not against the Nc-1 isolate of N. caninum. In vivo studies in N. caninum (Nc-1 isolate) infected mice showed that daily intraperitoneal application of DB745 for a period of 14 days resulted in a decreased number of clinically affected animals, and lower cerebral parasite burdens in DB745-treated mice compared to non-treated mice. These results illustrate the potential of dicationic arylimidamides for the treatment of N. caninum infections
The adaptive potential of a survival artist: characterization of the in vitro interactions of Toxoplasma gondii tachyzoites with di-cationic compounds in human fibroblast cell cultures
The impact of di-cationic pentamidine-analogues against Toxoplama gondii (Rh- and Me49-background) was investigated. The 72 h-growth assays showed that the arylimidamide DB750 inhibited the proliferation of tachyzoites of T. gondii Rh and T. gondii Me49 with an IC50 of 0·11 and 0·13 μm, respectively. Pre-incubation of fibroblast monolayers with 1 μm DB750 for 12 h and subsequent culture in the absence of the drug also resulted in a pronounced inhibiton of parasite proliferation. However, upon 5-6 days of drug exposure, T. gondii tachyzoites adapted to the compound and resumed proliferation up to a concentration of 1·2 μm. Out of a set of 32 di-cationic compounds screened for in vitro activity against T. gondii, the arylimidamide DB745, exhibiting an IC50 of 0·03 μm and favourable selective toxicity was chosen for further studies. DB745 also inhibited the proliferation of DB750-adapted T. gondii (IC50=0·07 μm). In contrast to DB750, DB745 also had a profound negative impact on extracellular non-adapted T. gondii tachyzoites, but not on DB750-adapted T. gondii. Adaptation of T. gondii to DB745 (up to a concentration of 0·46 μm) was much more difficult to achieve and feasible only over a period of 110 days. In cultures infected with DB750-adapted T. gondii seemingly intact parasites could occasionally be detected by TEM. This illustrates the astonishing capacity of T. gondii tachyzoites to adapt to environmental changes, at least under in vitro conditions, and suggests that DB745 could be an interesting drug candidate for further assessments in appropriate in vivo model
The adaptive potential of a survival artist: characterization of the in vitro interactions of Toxoplasma gondii tachyzoites with di-cationic compounds in human fibroblast cell cultures
The impact of di-cationic pentamidine-analogues against Toxoplama gondii (Rh- and Me49-background) was investigated. The 72 h-growth assays showed that the arylimidamide DB750 inhibited the proliferation of tachyzoites of T. gondii Rh and T. gondii Me49 with an IC50 of 0·11 and 0·13 μm, respectively. Pre-incubation of fibroblast monolayers with 1 μm DB750 for 12 h and subsequent culture in the absence of the drug also resulted in a pronounced inhibiton of parasite proliferation. However, upon 5-6 days of drug exposure, T. gondii tachyzoites adapted to the compound and resumed proliferation up to a concentration of 1·2 μm. Out of a set of 32 di-cationic compounds screened for in vitro activity against T. gondii, the arylimidamide DB745, exhibiting an IC50 of 0·03 μm and favourable selective toxicity was chosen for further studies. DB745 also inhibited the proliferation of DB750-adapted T. gondii (IC50=0·07 μm). In contrast to DB750, DB745 also had a profound negative impact on extracellular non-adapted T. gondii tachyzoites, but not on DB750-adapted T. gondii. Adaptation of T. gondii to DB745 (up to a concentration of 0·46 μm) was much more difficult to achieve and feasible only over a period of 110 days. In cultures infected with DB750-adapted T. gondii seemingly intact parasites could occasionally be detected by TEM. This illustrates the astonishing capacity of T. gondii tachyzoites to adapt to environmental changes, at least under in vitro conditions, and suggests that DB745 could be an interesting drug candidate for further assessments in appropriate in vivo model
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